hmac: test Debug impls (#149)

hmac/src/lib.rs

@@ -76,7 +76,7 @@
 //!   the [`Error`][std::error::Error] trait for error types)
 //! - `reset`: enables implementation of the [`Reset`][digest::Reset] trait
 //!   (note that it makes HMAC states bigger)
-//! 
+//!
 //! [`digest`]: https://docs.rs/digest
 //! [`sha2`]: https://docs.rs/sha2
 //! [`RustCrypto/hashes`]: https://github.com/RustCrypto/hashes

hmac/tests/mod.rs

@@ -2,11 +2,20 @@
 use digest::new_mac_test as test;
 #[cfg(feature = "reset")]
 use digest::new_resettable_mac_test as test;
-use hmac::{Hmac, SimpleHmac};
+use hmac::{Hmac, HmacCore, SimpleHmac};
 use sha1::Sha1;
 use sha2::{Sha224, Sha256, Sha384, Sha512};
 use streebog::{Streebog256, Streebog512};
 
+#[test]
+fn test_debug_impls() {
+    fn needs_debug<T: std::fmt::Debug>() {}
+
+    needs_debug::<Hmac<Sha256>>();
+    needs_debug::<HmacCore<Sha256>>();
+    needs_debug::<SimpleHmac<Sha256>>();
+}
+
 // Test vectors from RFC 2104, plus wiki test
 test!(hmac_md5_rfc2104, "md5", Hmac<md5::Md5>);
 test!(hmac_md5_rfc2104_simple, "md5", SimpleHmac<md5::Md5>);